Following some links from Boing Boing, I came upon this

Using a series of 1:50 gear reductions, this motor, spinning at 200 RPM, will produce one revolution per every couple trillion years at the output shaft.

The output shaft is embedded in concrete.

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Arthur Ganson’s “Machine with Concrete”
The gear train on Arthur Gansen’s sculpture is driven at 200 rpm, and after stepping down 12 times, turns at a rate of less than one revolution per two trillion years. The final gear is embedded i……

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  1. great i guess before that time the concrete or one of the lats gears will break, great art work. As a kid i used to make such geartrains with the first technic lego, trying to make a perpetumobile 😉